To date, such improvised explosives have not been a credible threat on the battlefield, especially in improvised explosive devices. In Iraq, a few failed attempts were made using industrial chemicals, but the Marine Corps considers improvised WMDs a threat that’s likely, according to a contract solicitation from the service seeking assistance in developing this new training.

Marines with 1st Explosive Ordnance Disposal Company at Camp Pendleton will attend the new Weapons of Mass Destruction Design and Defeat Course in October. The goal is to improve EOD techs’ chances for survival should they encounter improvised WMD, and help deployed forces adapt to the threat.

It is a matter of time before improvised WMD are used against U.S. forces, says Steven Bucci, a foreign policy expert at the Heritage Foundation think tank in Washington. Bucci, a retired Army Special Forces officer, said attempts in Iraq demonstrated the enemy’s willingness to use them. All they lack are the materials, and failing states like Syria, which possess weaponized chemical agents, could provide them.

Improvised WMD would most likely incorporate chemical agents, Bucci said. While they are difficult to manufacture and weaponize, much of the work is done if enemy forces obtain chemical weapons from an unsecured national stockpile — artillery shells, for example.

“The bad guys know how to detonate artillery shells as IEDs,” Bucci said. “They did that in Iraq and Afghanistan. If they are chemical weapon shells or warheads, then you have a potential problem. So while that has not been a particular threat in the past — other than these lame attempts in Iraq — if they can get some of these things out of Syria, the possibility of creating chemical IEDs goes way up.”

An IED incorporating biological agents is unlikely, he said, because those are sensitive to heat and would likely be destroyed in a blast. A dirty bomb, which could be constructed by adding radioactive materials from medical devices to conventional explosives, is easy to manufacture if the materials are obtained.

Hence, the presence of weaponized chemical agents in unstable nations makes that the most likely threat.

The good news, Bucci said, is that those sorts of IEDs would not be a game changer. U.S. forces are already trained to operate in a chemical environment, and the repercussions are mostly psychological. Radiation exposure can be treated. An area hit by a dirty bomb can be cleaned relatively quickly. Chemical agents would only affect people in the immediate vicinity.

“It is not good to get lots of exposure to radiation, and chemicals could kill you right away,” Bucci said.

“But in both cases, the biggest danger remains the conventional explosive part of the IED. That is more likely to kill you than the other stuff.”